EHST 3600 1 LAST SESSION REVIEW • Wind velocity profile • Planetary boundary layer • Gradient wind • Maximum mixing depth • Rawinsonde measurements • Horizontal dispersion of pollutants • Wind speed and direction • Wind rose • Atmospheric turbulence • Thermal • Mechanical • Stack plume characteristics • Looping • Coning • Fanning • Fumigation • Lofting • Trapping • Plume behavior • Terrain • Buildings LAST SESSION REVIEW • Urban heat island effect • Human impact on earth-atmosphere system • Depletion of the ozone layer • Health and ecological effects • Rising levels of atmospheric CO2 DISPERSION OF POLLUTANTS IN THE ATMOSPHERE EHST 3600: Air Pollution SESSION OBJECTIVES • To know the dispersion of pollutants • To know the factors affecting dispersion of pollutants • To know micro- and macro-scale dispersion of pollutants • To know how to calculate effective stack height SESSION OUTLINE • Settling velocity • The eddy diffusion model • The Gaussian dispersion model • Calculation of the effective stack height ATMOSPHERIC DISPERSION OF EFFLUENTS FROM SOURCES • Physical and chemical nature of effluents • Meteorological characteristics of the environment • Location of the stack with relation to obstructions to air motion • Nature of the terrain downwind from the stack EHST 3600 2 SETTLING VELOCITY • Low settling velocity • Gases • Fine particles (20 um or smaller) • Larger settling velocity • Large particles • Results in a higher ground-level concentration of the solid pollutant closer to the stack than is the case for gases. • No wind speed • Low-density plumes tend to reach high elevations; ground concentrations are low • Large particles and dense gas plumes fall to the ground in the vicinity of the stack • High wind speed • Increases the diluting action of the atmosphere • Gives rise to lower ground- level concentrations downwind from the stack 𝑉𝑠 𝑢 ≥ 1.5 PREVENTION OF DOWNWASH To achieve maximum dispersion, the effluents should leave the stack with sufficient momentum and buoyancy that they continue to rise from the stack exit. 𝑉𝑠 𝑢 ≥ 1.5 • Stack gas velocity = 6.8 mph • Wind velocity on top of stack = 6.0 mph • Possibility of downwash? • If <1.5, calculate the reduced stack height: ℎ𝑠 ′ = ℎ𝑠 + 2𝑑𝑠 𝑉𝑠 𝑢𝑠 − 1.5 hs METEOROLOGICAL SCALES OF AIR MOTION Scale Geo. Area (km2) Time Period Meteorological Phenomenon Planetary scale Weeks- months Atmospheric circulation; Hadley cell flows; Tropical storms; Jet stream meanders; Cold & warm front Meso scale 15-160+ Hours- Days Land/sea breeze; Valley winds; Urban heat island Synoptic Scale >106 Days Migratory high & low pressure systems; Cold & warm fronts; Semi permanent high-pressure systems Micro scale < 10 Minutes Plume behavior; Building downwash ; Eddy currents THE EDDY D

1. EHST 3600 1
LAST SESSION REVIEW
• Wind velocity profile
• Planetary boundary layer
• Gradient wind
• Maximum mixing depth
• Rawinsonde measurements
• Horizontal dispersion of pollutants
• Wind speed and direction
• Wind rose
• Atmospheric turbulence
• Thermal
• Mechanical
• Stack plume characteristics
• Looping
• Coning

2. • Fanning
• Fumigation
• Lofting
• Trapping
• Plume behavior
• Terrain
• Buildings
LAST SESSION REVIEW
• Urban heat island effect
• Human impact on earth-atmosphere system
• Depletion of the ozone layer
• Health and ecological effects
• Rising levels of atmospheric CO2
DISPERSION OF POLLUTANTS
IN THE ATMOSPHERE
EHST 3600: Air Pollution
SESSION OBJECTIVES
• To know the dispersion of pollutants

3. • To know the factors affecting dispersion of pollutants
• To know micro- and macro-scale dispersion of pollutants
• To know how to calculate effective stack height
SESSION OUTLINE
• Settling velocity
• The eddy diffusion model
• The Gaussian dispersion model
• Calculation of the effective stack height
ATMOSPHERIC DISPERSION OF
EFFLUENTS FROM SOURCES
• Physical and chemical nature of effluents
• Meteorological characteristics of the environment
• Location of the stack with relation to obstructions to air
motion
• Nature of the terrain downwind from the stack
EHST 3600 2
SETTLING VELOCITY
• Low settling velocity

4. • Gases
• Fine particles (20
um or smaller)
• Larger settling velocity
• Large particles
• Results in a higher
ground-level
concentration of
the solid pollutant
closer to the stack
than is the case for
gases.
• No wind speed
• Low-density plumes tend to
reach high elevations; ground
concentrations are low
• Large particles and dense gas
plumes fall to the ground in
the vicinity of the stack
• High wind speed
• Increases the diluting action of
the atmosphere
• Gives rise to lower ground-
level concentrations

5. downwind from the stack
��
�
≥ 1.5
PREVENTION OF DOWNWASH
To achieve
maximum
dispersion, the
effluents should
leave the stack with
sufficient
momentum and
buoyancy that they
continue to rise from
the stack exit.
��
�
≥ 1.5
• Stack gas velocity = 6.8 mph
• Wind velocity on top of stack = 6.0 mph
• Possibility of downwash?

6. • If <1.5, calculate the reduced stack height:
ℎ�
′ = ℎ� + 2��
��
��
− 1.5
hs
METEOROLOGICAL SCALES
OF AIR MOTION
Scale Geo. Area
(km2)
Time
Period
Meteorological Phenomenon
Planetary
scale
Weeks-
months
Atmospheric circulation; Hadley cell
flows; Tropical storms; Jet stream
meanders; Cold & warm front
Meso
scale

7. 15-160+ Hours-
Days
Land/sea breeze; Valley winds; Urban
heat island
Synoptic
Scale
>106 Days Migratory high & low pressure systems;
Cold & warm fronts; Semi permanent
high-pressure systems
Micro
scale
< 10 Minutes Plume behavior; Building downwash ;
Eddy currents
THE EDDY DIFFUSION MODEL
• Any diffusion process by which substances are mixed in the
atmosphere or in any fluid system due to eddy motion
• Involves the use of the “mixing length” concept
• Basis of the most comprehensive approach to transport
theory
• Usual starting point in the development of a dispersion
model for the atmosphere
GAUSSIAN DISPERSION MODEL
Fig. 4-2

8. H = effective stack height
hs = stack height
• Stack characteristics
• Meteorological
conditions
• Physical and chemical
nature of the effluent
CALCULATION OF THE
EFFECTIVE STACK HEIGHT
• Determine if there is downwash of plume due to low exit
velocity
•
��
�
�
′ = ℎ�
•
��

9. �
height, ℎ�
′ :
• ℎ�
′ = ℎ� + 2��
��
��
− 1.5
�� - stack velocity (m/s)
� – wind speed measured at the height, ℎ�
ℎ� - physical stack height (m)
�� - stack exit diameter (m)
EHST 3600 3
CALCULATION OF THE
EFFECTIVE STACK HEIGHT
• Determine stability category:
• Unstable or neutral condition
• Stable condition
• Calculate the buoyancy flux, ��
• �� = �����
2 ��−��

10. 4��
• Calculate the difference between the stack gas and ambient
• ∆� = �� − ��
CALCULATION OF THE
EFFECTIVE STACK HEIGHT
dominated by
momentum or buoyancy
PROBLEM SOLVING
Example 4-6
• Wind speed at top of stack = 3 m/s
• Stack gas velocity = 6 m/s
• Stack diameter = 2 m
• Physical stack height = 40 m
• Atmospheric stability = neutral
• Air temp = 300 K

11. • Stack temp = 440 K
SUMMARY
• Settling velocity
• The eddy diffusion model
• The Gaussian dispersion model
• Calculation of the effective stack height
• Plume downwash
• Atmosphere stability conditions
• Buoyancy flux, Fb
• Difference betw
FINANCIAL ANALYLSIS PROJECT
AC 200 Survey of Accounting
Select a publicly traded corporation that has been in the news
recently. Analyze the corporation and

12. write a paper, which should be three (3) to five (5) pages long.
The components of the analysis / paper
should be:
provided, senior officials (e.g.,
Chairman of the Board of Directors, Chief Executive Officer
(CEO), Chief Financial Officer
(CFO), and President), headquarters location, size, etc.
financial statements for the last two
(2) to three (3) years (you can get summary financial statement
data from Google Finance, Yahoo
Finance, the selected company’s annual report, equity analysts,
and other sources)
financial statements: (1) current ratios,
(2) acid test ratios, (3) debt to equity ratios, (4) total asset
turnovers, and (5) returns on common
stockholder’s equity. Are the ratios improving or deteriorating?
Why?
lysis by
equity analysts as listed on Google

13. Finance or Yahoo Finance for the company; company annual
statements; Wall Street Journal or
Forbes articles, etc.). Do Not Use WIKI!
NOTE: Google Finance or Yahoo Finance provide links to
recent news, analysis by equity analysts,
annual report, Edgar (the U.S. Securities and Exchange
Commission website), and other significant
sources of information.
To summarize the organization of the paper is as follows:
Main Body- 3 to 5 pages
Reference page
Email the name of your corporation by midnight on September
22, 2014. Paper is due midnight on
September 28, 2014. You will upload your paper to a folder in
Week 5 (click on Financial Analysis
Projects in Assignments and you will find the folder).
EHST 3600: Air Pollution
EQUATIONS

14. � = ℎ� + ∆ℎ
��
�
≥ �� < 1.5
ℎ�
′ = ℎ� + 2�� [
��
��
− 1.5]
�� = �����
2 (
�� − ��
4��
)
� = 9.8 � �2⁄
∆� = �� − ��

15. EHST 3600: Air Pollution – Homework 2 1
EHST 3600 HOMEWORK 2
Calculation of the Effective Stack Height (10 points)
Instruction: Show ALL calculations. Submit on Sept. 27, 2016,
Tuesday in class.
The wind speed at the top of a stack was measured as 5 m/s,
while the stack gas velocity
was measured as 8 m/s. The stack has a height of 67 m, and a
diameter of 3.5 m. The
atmospheric stability condition is unstable, with a temperature
of 305 K. The stack
temperature is 480.
1) Is there a possibility of a downwash? Show all calculations.
(1 pt)
2) Calculate the buoyancy flux. Show all calculations. (1 pt)

16. 3) Calculate the crossover temperature difference. Show all
calculations. (2 pt)
EHST 3600: Air Pollution – Homework 2 2
4) Is the plume rise dominated by momentum or by buoyancy?
Explain through
calculations. (2 pt)
5) Calculate the plume rise. Show all calculations. (2 pt)

17. 6) Calculate the effective stack height. Show all calculations. (2
pt)
EHST 3600: Air Pollution – Homework 2 3
EXTRA CREDIT (5 POINTS) (to be added to Exam 2)
NOTE: You must show ALL calculations to get credit.
The wind speed at the top of a stack and the stack gas velocity
were measured as 5 and 7
m/s, respectively. The stack diameter is 3 m with a 55-m
physical stack height. The
atmospheric stability condition is stable with a temperature of
290 K, and the stack
temperature is 475 K. The stability parameter, s, is 0.00068.
1) Is there a possibility of a downwash? Show all calculations.
(1 pt)
2) Is there a need to calculate the reduced stack height? If no,
explain why? If yes, calculate
the reduced stack height? (1 pt)
3) Calculate the crossover temperature difference. Show all
calculations. (1 pt)

18. EHST 3600: Air Pollution – Homework 2 4
4) Calculate the plume rise. Show all calculations. (1 pt)

19. 5) Calculate the effective stack height. Show all calculations.
(1 pt)